Hyperacute rejection is caused by:a. Preformed antibodies
Hyperacute rejection, a very rapid type of rejection, results in irreversible damage and graft loss within minutes to hours after organ reperfusion. It is triggered by preformed antibodies against the donor's human leukocyte antigen (HLA) or ABO blood group antigens. These antibodies activate a series of events that result in diffuse intravascular coagulation, causing ischemic necrosis of the graft. Fortunately, pretransplant blood group typing and cross-matching (in which the donor's cells are mixed with the recipient's serum, and then destruction of the cells is observed) have virtually eliminated the incidence of hyperacute rejection.